Document Definition Markup Language
Encyclopedia
Document Definition Markup Language (DDML) is an XML schema
language proposed in 1999 by various contributors from the xml-dev electronic mailing list
. It was published only as a W3C Note, not a Recommendation, and never found favor with developers.
DDML began as XSchema, a reformulation of XML DTD
s as full XML documents, so that elements and attributes, rather than declarations, could be used to describe a schema. As development continued, the name was changed to DDML, reflecting a shift away from the goal of replicating all DTD functionality, in order to concentrate on providing a robust framework for describing basic element/attribute hierarchy. DDML offered no datatypes or functionality beyond what DTDs already provided, so there was not much advantage to using DDML instead of DTDs. DDML did, however, inform the development of the next generation of XML-based schema languages, including the more successful XML Schema and RELAX NG
.
XML schema
An XML schema is a description of a type of XML document, typically expressed in terms of constraints on the structure and content of documents of that type, above and beyond the basic syntactical constraints imposed by XML itself...
language proposed in 1999 by various contributors from the xml-dev electronic mailing list
Electronic mailing list
An electronic mailing list is a special usage of email that allows for widespread distribution of information to many Internet users. It is similar to a traditional mailing list — a list of names and addresses — as might be kept by an organization for sending publications to...
. It was published only as a W3C Note, not a Recommendation, and never found favor with developers.
DDML began as XSchema, a reformulation of XML DTD
Document Type Definition
Document Type Definition is a set of markup declarations that define a document type for SGML-family markup languages...
s as full XML documents, so that elements and attributes, rather than declarations, could be used to describe a schema. As development continued, the name was changed to DDML, reflecting a shift away from the goal of replicating all DTD functionality, in order to concentrate on providing a robust framework for describing basic element/attribute hierarchy. DDML offered no datatypes or functionality beyond what DTDs already provided, so there was not much advantage to using DDML instead of DTDs. DDML did, however, inform the development of the next generation of XML-based schema languages, including the more successful XML Schema and RELAX NG
RELAX NG
In computing, RELAX NG is a schema language for XML, based on Murata Makoto's RELAX and James Clark's TREX. A RELAX NG schema specifies a pattern for the structure and content of an XML document...
.